The Apple (AAPL) Store has revamped the way it lists the top-selling online items, making it more difficult to tell whether iPhones are more popular than iPods or Macs.

Up until the past few days, Apple displayed one list of the top-selling items across all of its product categories at store.apple.com. That list tended to show that the iPod nano was the company’s best-selling single item, followed by the iPod classic and iPod touch. The MacBook laptop typically showed up in fourth or fifth place, with the iPhone nearby.

With Apple’s new listing system, it separates products by category. All computer-related items are listed together, then all iPod-related items, and all iPhone-related items.

The effect, intended or not, is that it is more difficult to tell how much last month’s iPhone price cut is moving the needle on sales. (Apple sells a healthy proportion of its product through its popular online store, which made it a decent barometer of a product’s overall appeal.)

Apple’s new listing method does offer good news for Apple investors, however: Early signs indicate that Apple’s new iPod product lineup will yield healthy profit margins. The second-best-selling iPod today, behind the nano, is the new flash memory-based iPod touch, which starts at $299. The iPod classic, which has more storage and a lower price tag, is number three. Amazon.com’s (AMZN) electronics top-seller list shows the same trend; on its list the nano is the most popular iPod, followed by one version of the classic and two versions of the touch.

Generally speaking, better sales of higher-priced iPods suggest higher profit margins.